Most important thing for me on a commercial product is in general the wish, to understand the theory of operation in detail. Unfortunately this is impossible without a schematic diagram. OTOH - most exist schematic diagrams from today's available audio devices wasn't release, because this diagrams are confideltial in most cases.

But in this case only the information concerning the used semiconductors U1 and U5 from the internal SMPS regulator with SMD marking code "EAA 5SA" and "OQ = H05" or "0Q = HO5" is important for me (I am already owner of this RIAA preamp device).

The actually supply voltage for the input stages and RIAA stages are create by internal SMPS DC/DC concerter.

This provides the great addvantage, that both the quality and technology (both 50/60Hz or SMPS) of/in the outdoor wall power plug haven't any influence to the sonic character. Even a high proportion of disturbances in the power grid haven't any influence through this approach.
OTOH - the quality of the internal SMPS defines the highest achievable quality in sound.

I think, a creating of schematic is impossible, because the used marking codes on the transistors are custom made, at least partly.
According the marking codes underMarking smd
at the MC input stage operates a small signal N-Ch MOSFET (NXP 2N7001/12t) and a small signal NPN BjT (ONSEMI 2N4401/2x) in parallel mode. I doubt very strongly, whether this is possible.
The use of custom made marking for smd devices is a really good prevent for unauthorized clones resp. copies.